Method and means for the polychrome offset printing



June 6, 1950 u urr 2,510,388

METHQD AND MEANS FOR THE POLYCHROME OFFSET PRINTING Filed Jan. 20, 19472 Sheets-Sheet l June 6, 1950 G. DUBUIT 2,510,388

METHOD AND MEANS FOR THE POLYCHROME OFFSET PRINTING Filed Jan. 20, 19472 Sheets-Sheet 2 Patented June 6, 1950 METHOD AND MEANS FOR THE POLY-CHROME OFFSET PRINTING Louis Gilbert Dubuit, Paris, France lApplicationJanuary 20, 1947, Serial No. 723,021 In France May 25, 1946 10 Claims.

The polychrome off-set printing including the successive transfer of aplurality of monochrome the grade of the ink t be-used. As a matter offact, if the inks of various colors which areto be used for printing areall=of the same kind and of the same viscosity; there is produced on theblanket during thaexectitionof the machines to be printed mixturesbetweenlthe colors which blend together so that it is necessary tospeedily stop the operation inorder to clean-the blanket andthe plates.In order to 'avoid'this drawback one is led touse' for each color inkthenature and the viscosity of which are sufliciently different fromthose oftheinks of'the other colors forsuch mixings of the colors tobecome impossibleythis leads to a considerable complication andrestrictssubstantially the field of application of the printing"methodponsidered.

My invention has for its object a method which allows removingthe-above' 'drawbacks whereby it is possible to use for polychromecit-set print ing, printing inks ofany 'type without-it being necessaryto take into account their nature or their relative visco'sities. Myimproved'method consists chiefly in eliminating from each plate aftereach'transfer operation of said p'late on to the blanket and beforeany'further inking of said plate theink which is still adherent to thelatter after the transfer operation.

It has been found as-a matter of'fact, that such a cleaning of the platebetween the successive transfers is sufiicient to prevent anyobjectionab le mixing between the colors. This cleaning may be executedby means of a roller of rubber orthe'like material similar to therollers in current use for hiking the plates, said rollers being merelymoved over the plate after the transfer operation, while the inkingroller or rollers are held" away from said plate. The ink which stilladheres to the latter -is then collected by the rollerfrom "which it"may -'-be removed for instance-by a scraper.

The method according-to my invention-is of particular advantage inrotary machines of a type known; per -se which are adaptedfor the-offsetprintingon cylindrical and the like objects, for instance, such astubes.

In this case/the plates and the blankets are wound respectively overcorrespondingcylinders, the blankets rolling'in:contact-with all-theplates in" succession. "The-arrangement forexecuting the inventionmaythen include 'fore'achmono chrome platea rocking support'pivotailysecured to'the frame of the machine to be'printed and carrying on onehand an inking roller 'and'onthe other hand, a cleaning roller. Therockingof said support bring alternatingly 'thetwo' rollers into contactwith'the plate considered, said support cooperating with a cam rigidwith the cylinder carrying the blanket and producing 'the rocking ofsaid support during thepassage of the plate" in contact with blanketsand during a'fraction of the rotation of the blanket carrying cylinderpreceding saidpassage; this rocking is performed in thedirectionbringing the inking roller into contact with the. plate anditis :again provided during the 'remainderof theflrotation of thecylinder "considered in the oppositedirection'which brings the cleaningroller into contact with the plate, a'return spring connecting :therockingsupport'with the frame of the ma'chine and urging said supportinto contact'with the cam.

"It is of advantage to proce'ed'with-the adjust* ment of the" pressureurgingthe rollers against the plate at least as concerns the "inking.-roller. To this purpose, the latter roller or the two rollers used forinking and cleaning;maybe-mounted for instance, in an adjustablemannerzron-their rocking support. It is however preferable .to'use asuppoitmade of two independent'rparts;":say two arms which areadvantageously pivotally secured to a common'shaft and which .are'connected through a spring or the like elasticme'ans urging them towardsone another while at least one adjusting screw is provided forlimitingthe stroke of either of the arms carrying'the inking roller of both thearms formingthe"rollerfisupports. In the case of a single screw, "thelatter maybe rigid with the arms carrying'theinking roller and cooperatewith a'stopparriedby the arm carrying the cleaning roller or reversely.In the case of two adjusting screws',"the latter are preferably carriedeach by the 'c'orrespondingiarm and cooperate with a stationary stopcarried by the frame of the machine, projections carriediby each armcooperating with one anotherfor-lprovidinga minimum spacing b'etween the:latter, which spacing should be sufficiently'large for the two rollersto be incapable of coming -simultaneously into contact with' the plate;the -arrangement of two adjusting screws allows a modification asdesired of the pressures exerted on the plate by each of the inking andcleaning rollers.

The rocking support carries -preferably a scraper adapted to cooperate"with the cleaning roller, said member being for instance constituted bya mere blade carrying a bucket adapted to receive the ink removed fromthe roller considered.

I have shown diagrammatically in accompanying drawings a form ofexecution of an arrangement according to my invention as applied to arotary machine for three color off-set printing on objects such astubes, for instance of carboard or aluminium.

In said drawings:

Fig. 1 is a general diagrammatic view showing the mounting of severalarrangements according to my invention on a printing machine.

Fig. 2 is a diagrammatical view at a larger scale of a singlearrangement according to my invention.

The printing machine (Fig. 1) comprises as known per se a rotarycylinder I to a portion of the periphery of which is secured in theusual known manner a blanket 2 for the transfer of the impression. Thecylinder I is mounted in the usual manner on a frame which is notillustrated and which includes radial supports 3, carrying incorresponding bearings each a cylinder 4 carrying a printing plate 5corresponding to one of the colors of the three-chrome printing.

To a shaft 5, rigid with each radial support 3 are pivotally secured twoindependent arms I and 8. The arm I carries an inking roller 9 of rubberof a type known per se, while the arm 8 carries a cleaning roller insimilar to the roller 9.

The plate carryin cylinder t is adapted to rotate in a manner known perse, under the action of a gear cooperating with a toothed wheel rigidwith the cylinder I. The roller 9 is mounted loose while the roller I isadapted to rotate at a peripheral speed which is equal to that of theplate under the action of a gearwork carried by the arm 8 and includinga toothed wheel I! receiving its movement from the shaft I2 of thecylinder I also through the agency of a gearwork. The system oftransmission members which has just been mentioned has not beenillustrated in the drawings in order to not overcrowd the latter, buttheir mounting shows no particular difficulty and is within the scope ofany mechanic.

The members for bringing ink to and distributing it over the roller Illand the members adapted to hold the objects which are to receive theimpression and to bring them into contact with the transfer roller,difier by no means from the similar members already used in similarmachines in current use and they have therefore not been illustrated.

The arms I and B are permanently urged towards one another by a returnspring I3 and carry respectively projections I 4 and I5 facing oneanother, said projections having a length such that when they are incontacting relationship they provide between the rollers 9 and III asufficiently large spacing for said rollers not to be capable of cominsimultaneously into contact with the plate 5. These arms carry alsoadjusting screws shown respectively at I6 and I1 and cooperating'eachwith one side of a common abutment I8 rigid with the correspondingsupport 3.

The arm 8 is provided with a scraper I9, the edge of which bears againstthe surface of the cleaning roller I0, said scraper carrying a bucket orrecess 21? adapted to receive the ink scraped ofi the roller Ill. Forsake of simplicity said scraper has been illustrated as stationary butit may be pivotally secured to its support and urged by a spring againstthe surface of the roller I0.

This same arm 8 which is urged towards the support 3 by a spring 2icarries at its free end a roller 22 cooperating with a cam 23 rigid withthe cylinder I and cooperating with all the similar rollers 22 of allthe inking and cleaning arrangements distributed over the periphery ofsaid cylinder I. The outline of this cam is such that for eacharrangement, the cleaning roller I0 is moved away from the plate 5against the action of the spring 2| durin the passage of said plate overthe blanket 2 and during the period preceding said passage whichcorresponds to about two revolutions of the cylinder 4 while during theremainder of the rotation of the cylinder I said roller I0 is submittedunrestrictedly to the return action of the spring 2 I The description ofthe operation of the machine given hereinafter corresponds only to theexistence of a single plate carrying arrangement, the operation beingthe same for all these arrangements.

The cylinder carrying the blanket 2 is set rotating through the usualmeans in a direction given out by the arrow, and the plate 5 carried bythe cylinder 4 starts also rotatin together with the rollers 9 and I0.When the cam 23 engages the roller 22 at the point 24 (Fig. l), the arm8 is urged to rock against the action of the spring 2| and the roller I0is moved away from the plate 5. The movement of the arm I beingassociated with that of the arm 8 by the spring I3, said arm I is causedto rotate clockwise until the adjusting screw I6 abuts against the stopI8. The screw I6 is previously adjusted so that under said conditionsthe roller 9 may bear against the plate with the pressure required forthe correct inking of the latter. The plate 5, is then filled with inkof the required color, and when its passes over the blanket 2 istransferred on to the latter.

The cylinder i prosecuting its rotation, the cam 23 leaves the roller 22at a point 25. The spring 2| urges then the arm 8 into contact with thecylinder. The projection I5 comes into contact with the projection I4and urges it back so that the roller 9 is moved away from the plate 5,while the roller Ill bears against the latter, the screw I! beingadjusted to this purpose. During the contact between the plate 5 and theroller ID, the latter collects the ink covering said plate, said inkbeing removed from the roller ID as it rotates by the scraper IS. Theroller 22 is then reengaged by the cam 23 and the oper-- ation beginsover again.

At each revolution of the cylinder I, the different plates are thustransferred on to the blanket, which is caused subsequently to move overthe objects to be printed which assume, in a manner well known per se, acorresponding rotary movement, said object receiving then the impressiontransferred on to the blanket.

What I claim is:

1. In an arrangement for off-set polychrome printing applicable torotary machines including a cylinder for the blanket and a plurality ofcylinders for the plates to be inked in different colors and transferredon to the blanket, the combination with each monochrome plate carryingcylinder of a support, a stationary pivot to which said support isrockingly secured, an inking roller and a cleaning roller carried bysaid support and means whereby the rocking of the support brings inalternation the two rollers into contact with the plate, a cam rigidwith the blanket carrying cylinder, and adapted to provide the rockingof atlases thersupnortvduringrthe -passagehitherplate over theblanketand during. a" fraction-of the rotation of the: blanket: carryin:cylinder preceding :said passage rin: a direction? bringingronerroilerinto contact with the plate and a-spring connected withthe rockingsupport and urgingsaidsupport against the cam and blanket carryingcylinder for rocking the support in the opposite direction withreference to vthe'plate carrying cylinder and bringing the: other rollerinto .-contact with :the plate.

2; ,In; anarrangement .for offset polychrome printing. applicabletorotary machines includin a .cylinder for the-blanketv andza plurality ofcylinders vfor theplates to be vinked indifferent colors and transferredonto the blanket-thecom- :binatiomwith each'monochrome plate carryingcylinder of: a'support, a stationary: pivot: to which saidisupportisrockinglysecured, an inking roller and. ascleaning roller ,carriedzbysaid: support, meansfor adjusting the pressure. ;applied by! at leastthe. inking roller-on the plate and-means whereby: the'rocking-ofnthesupport-1 brings in alternation: .the two rollers into..-contact-.withthe plate; .acam rigid 'withzthelblanket carrying cylinder, and adaptedto provide the rocldng of the support durin the passage of the plateover the blanket and during a fraction of the rotation of the blanketcarrying "cylinder preceding said passage in a direction bringing oneroller into contact withltheplate and a spring connected with therocking support and-urging said support against the cam and blanketcarrying-cylinderflforrocking the supportcin the ;opposite directionwith reference to the-plate, carrying cylinder and bringing the otherroller into contact with the plate.

3. In an arrangement for off-set polychrome printing applicable torotary machines including a, cylinder for the blanket and a plurality ofcylinders for the plates to be inked in difierent colors and transferredon to the blanket, the combination with each monochrome plate carryingcylinder of two members, a stationary pivot for same, a spring urgingsaid members towards one another, means for limiting the movement of themembers towards one another, an inking roller and a cleaning rollercarried respectively by each of the two members, a cam rigid with theblanket carrying cylinder and cooperating with one member for urging oneof the inking and cleaning rollers away from the plate carrying cylinderand yieldingly engaging the other roller into contact therewith andyielding means urging the cam follower against the cam and blanketcarrying cylinder surface beyond the cam and thereby urging the firstcylinder into contact with and the second cylinder out of contact withthe plate carrying cylinder.

4. In an arrangement for off-set polychrome printing applicable torotary machines including a cylinder for the blanket and a plurality ofcylinders for the plates to be inked in diiferent colors and transferredon to the blanket, the combination with each monochrome plate carryingcylinder of two members, a stationary pivot for same, a spring urgingsaid members towards one another, an adjusting screw cooperating with atleast one member, an abutment on the other member against which saidscrew is adapted to hear an inking roller and a cleaning roller carriedrespectively by each of the two members, a cam rigid with the blanketcarrying cylinder and cooperating with one member for urging one of theinking and cleaning rollers away from the plate carryingscylinder. landyieldingly engaging-the other .rollerinto contact,,therewith-. andyielding means. urging ,the cam i follower against the .cam and-blanket-.carrying cylinder surf ace) beyond .thacam and,.thereby. urgingthefirst cylinder into-contact (with and the'second cylinder out ofcontactwithtthe plate carrying cylinder.

v .5. In. an arrangement tor oil-set polychrome printing applicable torotaryernachines includinga cylinder for the blanket and a plurality ofcylinders for :the plates to-beinked in different colors andrtransferred on to the blanket, the combination-i-with each monochromeplate carryinggcylinder-of: two members, a stationary pivot forsame;aspring urging said members towards one anothentwo adjusting'screwscarried by the correspondingamembers, a stationary stop cooperating.with both screws projections facing one, another on-thetwo members andadapted to meet for preventing the spacing between said parts fromfalling underneath a predetermined value, an inking roller and acleaning roller carriedrespectively'by each of the two members, a camrigid with the blanket carrying cylinder and-cooperating with vonemember for urging one of the. inking and cleaning .rollers away from theplate-carrying cylinder and'yieldingly engaging the other-roller intocontactitherewith and yieldinglmeans urging the cam follower against thecam and blanket carrying cylinder surface beyond theca-m and'thereby.urging the first cylinderinto contact with and the second cylinder outof con tact with the plate carrying cylinder.

6. Inuanarrangement for ofi-set polychrome printing applicable to rotarymachines including a cylinder for the blanket and a plurality ofcylinders for the plates to be inked in difierent colors and transferredon to the blanket, the combination with each monochrome plate carryingcylinder of a support, a stationary pivot to which said support isrockingly secured, an inking roller and a cleaning roller carried bysaid support and means whereby the rocking of the support brings inalternation the two rollers into contact with the plate, a cam rigidwith a blanket carrying cylinder, and adapted to provide the rocking ofthe support during the passage of the plate over the blanket and duringa fraction of the rotation of the blanket carrying cylinder precedingsaid passage in a direction bringing one roller into contact with theplate, and a spring connected with the rocking support and urging saidsupport against the cam and the blanket carrying cylinder for rockingthe support in the opposite direction with reference to the platecarrying cylinder and bringing the other roller into contact with theplate, and a scraper cooperating with the cleaning roller for removingthe ink therefrom.

7. In an arrangement for oiT-set polychrome printing applicable torotary machines including a cylinder for the blanket and a plurality ofcylinders for the plates to be inked in difierent colors and transferredon to the blanket, the combination with each monochrome plate carryingcylinder of two members, a, stationary pivot for same, a, spring urgingsaid members towards one another, means for limiting the movement of themembers towards one another, an inking roller and a cleaning rollercarried respectively by each of the two members, a cam rigid with theblanket carrying cylinder and cooperating with one member for urging oneof the inking and cleaning rollers away from the plate carrying cylinderand yieldingly engaging the other roller into contact 7 therewith andyielding means urging the cam follower against the cam and blanketcarrying surface beyond the cam and thereby urging the first cylinderinto contact with the second cylinder out of contact with the platecarrying cylinder, a scraping blade yieldingly carried by the samemember as the cleaning roller and adapted to cooperate therewith andmeans rigid with said blade for collecting the ink removed by said bladefrom said cleaning roller.

8. In an arrangement for oiT-set polychrome printing applicable torotary machines including a cylinder for the blanket and a plurality ofcylinders for the plates to be inked in different colors and transferredon to the blanket, the combination With each monochrome plate carryingcylinder of a support, a stationary pivot to Which said support isrockingly secured, an inking roller and a cleaning roller carried bysaid support and means whereby the rocking of the support brings inalternation the two rollers into contact with the plate, a cam rigidwith the blanket carrying cylinder, a cam follower carried by therocking support for cooperation with said cam, and adapted to providethe rocking of the support during the passage of the plate over theblanket and during a fraction of the rotation of the blanket carryingcylinder preceding said passage in a direction bringing one roller intocontact with the plate and a spring connected with the rocking supportand urging said support against the cam and blanket carrying cylinderfor rocking the support in the opposite direction with reference to theplate carrying cylinder and bringing the other roller into contact withthe plate.

9. In a polychrome off-set printing method including the successivetransfer of a plurality of monochrome plates on a single blanket; thesteps of removing the plates from the blanket after each transferoperation, removing the inking cylinder from each plate when the latteris removed from the blanket and removing the ink from the plate bypassing the entire surface of the plate at least twice in contact with ayielding roller of the plate inking type, and reinking said plate anewin contact with the blanket.

10. In a polychrome ofi-set printing method including the successivetransfer of a plurality of monochrome plates on a single blanket, inwhich a plurality of blankets are mounted on the same blanket cylinder;the steps of removing the plates from the blankets after each plate hascontacted all of the blankets, removing the inking cylinder from eachplate when the latter is removed from the blankets and removing the inkfrom each plate by passing the entire surface of said plate at leasttwice in contact with a yielding roller of the plate inking type, andreinking said plate anew in contact with the first blanket.

LOUIS GILBERT DUBUIT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 752,896 Firm Feb. 23, 19041,743,656 Cox Jan. 14, 1930 2,106,104 Massey Jan. 18, 1938

